Cat 3116 fuel supply problem.

Hello everyone. Todd here from Utica NY. I have a 92 GMC C7500 forestry bucket truck with a Cat 3116. I had the usual long crank cold start and smoke issue. I am not a believer of fixes in a bottle but I added Stiction Reducer to the fuel and it did clear up the cold start and smoke issue, for the most part.

The engine was running good when I parked it. I started it the following day and it stalled after 5 min of idling and has not started since. That was back in March. The engine will fire using starting fluid. So far I have replaced the return fuel pump located under the driver step up. I replaced the fuel filters. I replaced the plastic fuel supply line coming from the tank. I do Not have a manual priming pump. So to prime I tried pressurizing the tank and I even put my vacuum pump on the return line and I can't get fuel to flow. I moved the sleeve that covers the governor linkage and it pulls in toward the governor with key on. I read that that linkage is a known failure point because of a clip that falls off. I'm not sure if my clip has failed as I do not know where it is located exactly. My next step was going to be remove the rocker cover and check the rack movement with key on. My thoughts were if the rack is not moving to the fuel on position then that would explain why I can't get fuel to flow through the system. I am not a Diesel mechanic and I don't have special cat tooling but I am the fixer/mechanic of my own equipment and I can follow directions. I am open to any suggestions. Thanks in advance.

AM, sound like you have gone thru a lot of items, to double check your fuel supply I would use an aftermarket electric fuel pump plumb it in somewhere easy to use pump to push fuel to engine, crack open line at engine to check fuel flow (seen cigarette butt block tank pick up occasionally before) once you have fuel to engine I would check the movement on the solenoid it self (seen shaft break on them) I have never worked on that series of engine but this would be my steps to ensure you have fuel and open rack, I hope this helps?

Yes. I actually have a external fuel pump laying around. I will try that and just pump from a Diesel can. I was able to get to the return line check valve and I confirmed it was in working order. I was not able to get to the supply line screen located in the joint over top of governor but I did not spend much time trying either. I read that some cat 3116 engines came with no screen at that junction. Is that the only likely choke point on the supply side after the filter, assuming I have a screen?

Check the first fitting after the fuel tank. I have found a lot of tractors will block there. I have removed earwigs, grass, dearth from making the tanks and all sorts of other rubbish. The first fitting is a restriction that can catch rubbish and restrict fuel. Good luck.

A methodical approach would start at the tank, remove the outlet and check you have flow (like let it run for a good 30s), replace that connection and go to the next one, check the flow there, etc., etc. If you get all the way to the pump, then remove the injection lines and crank it with the governor control open. If nothing, then start digging into the pump, again following the flow so you don't miss a step in its sequence

I'm also suspicious about the last thing that changed, namely adding the fluid to the fuel. I would suspect that that has loosened up some crud somewhere in the system which resulted in a block. So any inline screens/filters may be clogged. You'll find that as you work through the flow. If it's clogged somewhere, then it'd be advisable to go right through all the system, cleaning components and screens and replacing filters. Wouldn't be a bad idea to drain the tank via those large paper filters and then cleaning it out too.

Ok. I will go through the fuel system and clear any crud. I will report back with my progress.